Table of Contents
Photo credit: Annie Spratt
Basic access authentication dates back to 1993 and it’s still heavily used today. The
server provides a
WWW-Authenticate header to the client and the client responds with
Authorization header and a base64-encoded (not encrypted) string to authenticate.
When done over a secure TLS connection, this method of authentication works well.
Traefik is an application proxy that takes requests from clients and routes them to different backends. You can use it by itself, in conjunction with Docker, or in a kubernetes deployment. I love it because it gets most of its information and configuration details from the environment around it. I don’t have to tell Traefik where my services are. It knows where they are based on the resources I add in kubernetes.
In this post, I’ll explain how to add kubernetes resources that allow Traefik to handle basic authentication for backend applications. This particular example covers authentication for Traefik’s dashboard. The dashboard displays lots of helpful diagnostic information about routing and services that helps you troubleshoot configuration errors.
On the other hand, this information is also quite useful to attackers and it’s a good idea to keep it hidden away. 🕵🏻
Important ingress #
Kubernetes aficionados know the ingress resource type well. It’s a resource that signals to a load balancer how it should route traffic within the cluster. Here’s an example:
apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: test-ingress spec: rules: - host: "foo.bar.com" http: paths: - pathType: Prefix path: "/bar" backend: service: name: service1 port: number: 80
This ingress takes traffic to
foo.bar.com underneath the URI
/bar and sends it to
service1 on port 80. Most kubernetes load balancers can take this
information and begin routing requests.
Traefik takes this up a notch with the IngressRoute resource. This CRD is Traefik-specific, but it makes configuration easier:
apiVersion: traefik.containo.us/v1alpha1 kind: IngressRoute metadata: name: ingressroutetls namespace: default spec: entryPoints: - websecure routes: - match: Host(`your.example.com`) && PathPrefix(`/tls`) kind: Rule services: - name: whoami port: 80 tls: certResolver: myresolver
We now have access to specify which Traefik entry points to use (these are ports that
Traefik listens to) as well as a certificate resolver of some sort. We can match the
host header and URI prefix on the same line with complex rules and send the traffic to
whoami service on port 80.
Our goal from here on out will be to:
- Add basic authentication to the traefik dashboard
- Enable the traefik dashboard so we can reach it from the outside
Enable authentication for the dashboard #
I’m using flux to manage my kubernetes cluster (read more on that in yesterday’s post) and I’m using its HelmRelease resource type to deploy Traefik. You can follow along with the files in my gitops-ng repository.
First, we need a namespace in
apiVersion: v1 kind: Namespace metadata: name: traefik
Let’s deploy Traefik using a HelmRelease resource and store this in
apiVersion: helm.toolkit.fluxcd.io/v2beta1 kind: HelmRelease metadata: name: traefik namespace: traefik spec: interval: 5m timeout: 20m install: crds: CreateReplace upgrade: crds: CreateReplace chart: spec: chart: traefik version: "10.19.4" sourceRef: kind: HelmRepository name: traefik namespace: flux-system # https://github.com/traefik/traefik-helm-chart/blob/master/traefik/values.yaml values: ports: web: redirectTo: websecure
I’m specifying that I want to install Traefik’s helm chart (version 10.19.4) into the
traefik namespace and I want to update the CRDs (which gives me the IngressRoute
resource type) on installation and during updates. At the end, I specify that all
non-secure HTTP requests on port 80 should be redirected to a TLS connection.
Now we need to set up the dashboard by creating a
--- apiVersion: traefik.containo.us/v1alpha1 kind: Middleware metadata: name: dashboard-ingress-auth namespace: traefik spec: basicAuth: secret: dashboard-auth-secret removeHeader: true --- apiVersion: traefik.containo.us/v1alpha1 kind: IngressRoute metadata: name: traefik-dashboard namespace: traefik spec: entryPoints: - websecure routes: - match: Host(`traefik.example.com`) kind: Rule middlewares: - name: dashboard-ingress-auth namespace: traefik services: - name: api@internal kind: TraefikService tls: certResolver: letsencrypt
Middleware resource specifies that I want basic authentication using the
dashboard-auth-secret secret (which we will create momentarily). The IngressRoute
specifies that all traffic coming to the
websecure TLS-secured frontend that is
traefik.example.com should be redirected to the internal Traefik
api@internal. Before that happens, the
must be applied.
👀 In my case, I have a certificate resolver called
letsencryptalready configured. This is outside the scope of this post, but the ACME docs have good examples of HTTP and DNS validation for certificates from LetsEncrypt.
Now we reach the tricky part. We need to create a username and password combination for
basic authentication and store it in a secret. The easiest method here us to use
htpasswd, create a secret from the file it creates, and then encrypt the file with
$ htpasswd -nB secretuser | tee auth-string New password: Re-type new password: secretuser:$2y$05$W4zCVrqGg8wKtIjOAU.gGu8MQC9k7sH4Wd1v238UfiVuGkf0xfDUu $ kubectl create secret generic -n traefik dashboard-auth-secret \ --from-file=users=auth-string -o yaml --dry-run=client | tee dashboard-auth-secret.yaml apiVersion: v1 data: users: c2VjcmV0dXNlcjokMnkkMDUkVzR6Q1ZycUdnOHdLdElqT0FVLmdHdThNUUM5azdzSDRXZDF2MjM4VWZpVnVHa2YweGZEVXUKCg== kind: Secret metadata: creationTimestamp: null name: dashboard-auth-secret namespace: traefik $ sops -e --in-place dashboard-auth-secret.yaml
Add all of the files we created into your flux repository or apply them with
kubectl apply -f (and consider embracing gitops later).
Access your Traefik dashboard URL and you should see a basic authentication prompt.
Enter the credentials you set with
htpasswd and you should see your Traefik dashboard!